Exploring One-Variable Data and Collecting Data unit test
A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.
Replication
Effect of an outlier on the standard deviation
Position of the median
Resistant measures
Locating the quartiles
Boxplot limitations
Working backward from a percentile
Purpose of a control group
Undercoverage
Parameter vs statistic
Bin width in a histogram
Scope of inference
Short answer 1. Define or explain: Social desirability bias
3 ptsShort answer 2. Define or explain: Why a large biased sample is worse than a small random one
3 ptsShort answer 3. Define or explain: Modified boxplot
3 ptsShort answer 4. Define or explain: Statistically significant in an experiment
3 ptsFree response
3 ptsAphids are tiny insects that feed on plants such as cabbage plants. A farmer wants to reduce the number of aphids in a cabbage field. A river is located 100 meters south of the field. The farmer divides the field into 25 regions of equal size, arranged in five rows of five regions each, with each region holding about the same number of cabbage plants: Row A (farthest north, beside the farmer's house): 1 2 3 4 5 Row B: 6 7 8 9 10 Row C: 11 12 13 14 15 Row D: 16 17 18 19 20 Row E (farthest south, nearest the river): 21 22 23 24 25 The farmer wants to estimate the proportion of cabbage plants in the field that are damaged by aphids, and believes damage is greater in regions closer to the river. Three sampling methods are considered: I. Select region 3 (closest to the house, farthest from the river) and examine every plant in it. II. Randomly select one row (A–E) and examine every plant in every region of that row. III. Randomly select one region from each of rows A, B, C, D and E, and examine every plant in each selected region.
A. Explain whether sampling method I is an appropriate sampling method for the farmer to use to estimate the proportion of cabbage plants in the field that are damaged by aphids.
B. Using sampling method II, the farmer randomly selected row E and examined every cabbage plant in row E. If the farmer’s belief is correct, determine whether the selection of row E is likely to provide an overestimate or an underestimate of the proportion of cabbage plants in the field that are damaged by aphids. Justify your answer.
C. Using the information provided in the diagram of the cabbage field, describe how to implement sampling method III, which requires a random selection of one region from each of rows A, B, C, D, and E.